An American admiral recently remarked that Russian submarine combat patrols had increased 50 percent over 2015. At least so far. No numbers were given, which is understandable as if the Russians know how accurate your data is they can better discover how you are obtaining it and make that more difficult. What the U.S. Navy is not talking about is how far behind the Russian submarine force has fallen since the late 1980s.
What is known is that Russia has, since the Soviet Union dissolved in 1991, had to cope with military budget cuts of over 80 percent. By the end of the 1990s the Russians began to turn that around but the damage to the mighty “Red Army” of the Cold War was done. By 1999 Russian armed forces were about 20 percent of their peak Soviet strength. The navy was hurt worst. The main problem was that Russian Navy not only shrunk since 1991 but it has also become much less active. Since the 1990s fewer and fewer of their nuclear subs went to sea on combat patrols. Most of the boats going to sea were SSNs (attack subs), not ballistic missile equipped SSBNs. Most of these trips were short range training missions, which often lasted a few days, or just a few hours. That was worse than it sounds because the true measure of a fleet is the "combat patrol" or "deployment." In the U.S. Navy most of these last from 2-6 months. Since 2001 U.S. nuclear subs have carried out ten times as many patrols as their Russian counterparts. Russia has been trying to turn that around by sacrificing their surface fleet to keep building a few nuclear subs and maintaining the most modern of their nuclear subs in service. But that was done at the expense of training. The nuclear subs rarely went to sea. Since 2010 that began to change but the dramatic fall in oil prices since 2013 and economic sanctions to punish Russia for attacking Ukraine have cut short plans for upgrading and expanding the nuclear sub fleet. Despite that nuclear subs have been to sea more recently, but by American standards Russian subs are barely visible out there.
The Russian admirals made their big mistake in the early 1990s when the dismantling of the Soviet Union left the second largest fleet in the world with only a fraction of its Cold War budget. Rather than immediately retire ninety percent of those ships, Russia tried to keep many of them operational. This consumed most of the navy budget and didn't work. There were too many ships, not enough sailors and not enough money for maintenance or training at sea. By the late 1990s the mighty Soviet fleet was mostly scrap or rusting hulks tied up at crumbling out-of-the way naval bases.
While Western nuclear subs can last for about thirty years Russian models rarely get past twenty. That means two new SSN or SSGN have to be put into service each year to maintain a force of forty Russian boats. Unless the sub construction budget get billions more dollars a year, that is not going to happen. Right now, the priority is on producing a new class of SSBNs (6 more Boreis are planned or under construction). These Boreis are essential because they carry SLBMs that provide a critical (they are much harder to destroy in a first strike than land based missiles) portion of the nuclear deterrent. The rest of the Russian armed forces, like most of the navy, are in sad shape and unable to resist a major invasion. Only the ICBMs and SLBMs guarantee the safety of the state. So the way things are going now, in a decade or two, Russia will end up with a force consisting of a dozen SSNs and a dozen SSBNs. Russian surface ships face similar life expectancy problems.