Mine is also difficult to calculate!
I started about 1968, + did nearly 6yrs of judo
I also spent the next few decades doing martial arts on horseback..
[which I haven't counted in my tally] and I'm *still* doing it!
I started karate just on 6 yrs ago
plus add to the total a year and half of WMA/medieval MA just for kicks!
If you counted what I've done with the horse related MA the grand total would be well over 40 years.