Per the graphic above, if your home was built before 1940 it is highly likely (87% chance) that your home contains lead-based paint. If your how was built between 1960-1977 there is approximately a 24% chance your home contains lead-based paint. In 1978 the federal government banned the commercial use of lead-based paint.
Source: https://www.epa.gov/sites/production/files/lead/images/olderhomes.jpg