There are a few different ways to calculate the years.
Some have been in and out of business, so the total years may not equal the number of years since the start of their first business. So the total number of years self employed in business might be the way to go.
Some have cleaned a little, off and on, when they were young as a part time job, perhaps for their parent or another employer. Then they later went into business for themselves.
Some where in the janitorial business, and just did carpet cleaning part time, if at all.
Some started out with a shampoo or dry foam method, but didn't get into steam cleaning when steam cleaning (hot water extraction) was in its infancy.
It would be interesting to see who has been steam cleaning the longest continually (or most years with steam).
So perhaps more than one kind of poll would be enlightening.
In answer to the above, I started my business in 1970 with a steam process and have used steam continually until 2012. From past posts over the years, I don't think I have noticed anyone else within the same parameters. Anyone out there I missed?
BTW, I have always done my own cleaning, never hiring a helper, unless you count my daughters once in a while to give them something to do, though they never actually did the cleaning. Also, my wife never worked elsewhere outside the home.