## GNU sed, 16 + 1(r flag) = 17 bytes

<!-- language: lang-sed -->

    s:.*([^0]0*):\1:

It works by deleting everyhting until the right-most nonzero digit that is followed by trailing zeros or nothing at all.

**Test examples:** the script can handle multiple inputs, one per line

<!-- language: lang-sh -->

    sed -rf efficient_count.sed << EOF
    > 2
    > 10
    > 11
    > 30
    > 99
    > 100
    > 120
    > 200
    > EOF
    2
    10
    1
    30
    9
    100
    20
    200