Newspaper circulation fell 2.6 percent in the six-month period ending in March, according to data released Monday, as the industry continued to struggle with competition from other media outlets and the Internet. The decline in average paid weekday circulation was about the same as the previous time newspapers reported six-month circulation figures for the period ending last September, according to the Newspaper Association of America, a trade group. The NAA reported that average paid circulation at Sunday newspapers fell 3.1 percent versus the same period a year ago, also a comparable decline with the last time circulation figures were reported....