select count(distinct event.searchSessionId) as total
from event.testsearchsatisfaction2
where year = 2018 and month = 9;

===

334155

===

select
    useragent.browser_family, 
    useragent.browser_major, 
    useragent.os_family,
    useragent.os_major, 
    count(distinct event.searchSessionId) / 334155 as percent
from event.testsearchsatisfaction2 
where year = 2018 and month = 9
group by useragent.browser_family, useragent.browser_major, useragent.os_family, useragent.os_major
order by percent desc 
limit 50;

===============

(above query with percent > 0.01)

Chrome  68      Windows 10      0.24833984228875822  
Chrome  68      Windows 7       0.16060810103095868  
Edge    17      Windows 10      0.048229115230955695
Firefox 61      Windows 10      0.03806915952177881
Safari  11      Mac OS X        10      0.034570783019856055
Chrome  68      Windows 8.1     0.03359818048510422
Chrome  68      Mac OS X        10      0.030111774475916866
IE      11      Windows 10      0.02915712768026814
Firefox 61      Windows 7       0.026813903727312176
IE      11      Windows 7       0.02441681255704688
Firefox 62      Windows 10      0.021457108228217444
Chrome  69      Windows 10      0.019966781882659244
Firefox 62      Windows 7       0.015555655309661683
Chrome  69      Windows 7       0.011976477981774925
Chrome  49      Windows XP      0.011626341069264263
Opera   55      Windows 10      0.01064176804177702