Without a single poll to back me up, the following could be said to
be accurate for 1911:

Any Frequency:
CW: 100% [on-off keying]

Someone inserted a carbon telephone microphone in
the feedline between the transmitter and antenna, and
produced a crude form of AM. Couldn't have been
much power else the mic would have burnt up. These
mics vary in resistance along with the sound they hear.

AM: 0%
Near but not = 0
SSB: 0%
RTTY: 0%
FM/NBFM: 0%
Other modes: 0%

VHF/UHF (all modes): 0%

Well, how far up did spark go?

In fact, there was NO ARRL and NONE of the amateur radio
enthusiasts were legal! [NO radio regulating agency active in
the USA in 1911] :-)

No, *all* activity on radio was legal. Anything not specifically
outlawed is legal. The radio regulations came later.