I have 15 & 16 recessed ears, both in good EF but still looking for a decent filled 5 1915 though.
I agree 1915 is harder - V R Court figures from circulation coins were
1915 277/2425 1 in 8.75 = approx mintage of 5.4 M
1916 921/4013 1 in 4.36 = approx mintage of 16.1 M
So approx 3 times as many 1916s than 1915s, and you have to search twice as many 1915s to find one
by comparison for other 20th C scarce pennies Court estimates the following mintages
1903 open 3 37,300
1908 F164a 55,550
1909 F169 23,200
1911 Gouby X 188,000
1926 ME 107,750
1946 dot 384,200
He didn't find any 1922/7, and no mention of the 1909 dot
Good luck folks for finding any of these in top grade!