Based on the percentage of people that had it, based on real testing from NY, so you can just put in this data for the whole world, i guess some places maybe less, but some places maybe more. it is also based on my own experience during the earlier month of FEB MAR and APR.
A. Based om the Data
On Apr 23th Gov Coumo announced based on the date and results 1 in 5 people in NY already had the virus as from sampling it shows 13.9 % percent tested positive for the antibodies and in NY City the rate is even higher at 21% percent , 13.9 % OF New Yorkers, The NY times wrote on Apr 23 that's about 2.7 Milllion New Yorkers.
So if you do the same calculations for the US, A population of 328 million, that is 45 millions only in the US alone,, but as of today Jun 30, the actual real figure of US cases is only 2.6 million.
now this data was from Apr 23rd, today is Jun 29th, so we probably have millions more infected.
just look in google search "1 in 5 new yorkers" or " 13.9 percent new york" this you will get lots of results just one of many articles link here
https://www.cbsnews.com/news/new-york-coronavirus-13-9-percent-coronavirus-antibodies-covid-19/
B. Based on my own experience.
I Had the virus early to middle MAR, i was around plenty of people and family prior of me knowing that i had it, i Also flew to London on Mar 1st and came back on Mar 9 , of all the people i was around no one got tested except one of my family member that is 75 yrs old., the reason why they didn't, because they didn't want to give the test than only if you showed serious symptoms like breathing problems only. i am 59 years , very healthy, so they didn't want to give me the test at first. the only reason why they gave me ok for the test was because my doctor recommended it, because i had a surgery on my throat , i had a abscess in my throat last year.
I Am not downgrading the seriousness of the virus, i am actually saying this virus is very catchy , if you live in NY example and you where in Restaurant, Train , plain or any store or park. or anywhere outside during Feb 15 thorough Mar 20 where most people didn't wear masks , you probably had it or you are immune to this.
you gotta also look back and think if you didn't feel good even just for a day or 2 in early 3 month of the year, there is a probability, that was the virus
what i am saying just , the virus is very catchy , but if you are healthy , a non smoker, not obese , not pregnant , don't need a Mask, even if you get it
it will be most likely just a very very light Flu.
so you make your decision , if you wanna enjoy life particular while getting a massage to wear or not wear a mask