Despite controversies over validity, the instrument has demonstrated widespread influence since its adoption by the Educational Testing Service in 1962. It is estimated that 50 million people have taken the Myers–Briggs Type Indicator and that 10,000 businesses, 2,500 colleges and universities, and 200 government agencies in the United States use the MBTI.
I’m also in my 40s, and I’ve flip-flopped between ISTP and INTP since my teens. I just took it again and today I’m INTP. Hooray for consistency, I guess…
p.s. if you take the test from the link, you do Not have to add your email to see your results. Don’t give your info away.