Yakuza Membership Decreasing

According to Japan's National Police Agency, the number of yakuza (Japanese mafia) members has decreased to 24,100 as of the end of 2021, which was down 1800 from the previous year. This is the lowest number since statistics began in 1958 and the seventeenth consecutive year of declining yakuza membership. 

End of 2021 membership in Japan's main gangs is shown below, with the year on year differences in number of members.

In 2021, 11,735 gang members were charged in a variety of criminal activities, down 1,454 from the previous year.  The largest number of arrests were for violations of the Stimulants Control Act (2,985), followed by fraud (1,555), assault resulting in injury (1,353), theft (1,008), violation of the Cannabis Control Act (764), in addition to 91 charges of murder.  

I wonder why membership is decreasing.  Are old members dying and not enough new members joining? Maybe police are cracking down on these criminals and they lose their membership when they go to jail. 

I've watched many programs about the American mafia families and the FBI or other agencies trying to arrest and convict them.  I did a quick google, but couldn't find the current number of members, but it does appear that their numbers are also decreasing.  Fewer criminals are a good thing, I think.