I just got a bit confused:

Numbers of registered users to last $$$3$$$ Div1 + Div2 combined contests: $$$12129$$$, $$$10160$$$, $$$8335$$$

Numbers of registered users to last $$$3$$$ Div2 only contests: $$$12266$$$, $$$11063$$$, $$$9832$$$.

BUT

Numbers of registered users to last $$$3$$$ Div3 contests: $$$13785$$$, $$$13216$$$, $$$12619$$$.

Of course, the time when the contest is held matters a lot, but still. Why do Div3 contests regularly gather so much more participants than Div2 and combined rounds? Div3 are rated for far fewer users than Div2 and combined rounds. Do low-rated coders avoid Div2 just because their problems just seem too hard?