I wonder how many people are carriers & only find out after genetic testing during pregnancy?

I have had asthma, eczema & allergies from an early age. My brother has asthma & seasonal allergies. My sister was diagnosed with CF only when she was in her 70's & I doubted this diagnosis until last year when my son tested as a CF carrier when his wife became pregnant & his wife was not. My daughter's genetic tests during her pregnancy showed she was not a carrier. My husband's daughter also is not a carrier & so I conclude that I must be a carriers