The national health interview survey conducted of 33,326 adults by the u. s. national center for health statistics in 2003 indicated that 21.4% of adults were current smokers. a similar study conducted in 1991 of 42,000 adults indicated that 25.6% were current smokers. we will use the subscript "1" for the year 1991 and the subscript "2" for the year 2003. (a) find a point estimate of the difference between the proportion of current smokers in 1991 and the proportion of current smokers in 2003. use 3 decimal places