How many share values are listed for the episode with a rating/share value of 2.6/8?
{'header': ['Episode #', 'US air date', 'Rating', 'Share', 'Rating/Share (18–49)', 'Viewers (millions)'], 'page_title': "Harper's Island", 'page_id': '', 'types': ['real', 'text', 'text', 'text', 'text', 'text'], 'id': '1-17525955-2', 'section_title': 'Ratings', 'caption': 'Ratings', 'rows': [['1', 'Thursday, April 9, 2009', '6.5', '11', '2.6/8', '10.21'], ['2', 'Thursday, April 16, 2009', '5.1', '9', '2.2/6', '7.82'], ['3', 'Thursday, April 23, 2009', '4.7', '9', '1.9/5', '7.02'], ['4', 'Saturday, May 2, 2009', '3.1', '6', '1.0/3', '4.61'], ['5', 'Saturday, May 9, 2009', '3.1', '6', '1.1/3', '4.60'], ['6', 'Saturday, May 23, 2009', '2.5', '5', '1.0/4', '3.85'], ['7', 'Saturday, May 30, 2009', '2.4', '5', '0.9/3', '3.62'], ['8', 'Saturday, June 6, 2009', '2.4', '5', '0.9/3', '3.56'], ['9', 'Saturday, June 13, 2009', '2.0', '4', '0.8/3', '3.20'], ['10', 'Saturday, June 20, 2009', 'TBA', 'TBA', '0.9/4', '3.79'], ['11', 'Saturday, June 27, 2009', '2.4', '5', '0.8/3', '3.53'], ['12', 'Saturday, July 11, 2009', '2.4', '5', '0.8/3', '3.63']], 'name': 'table_17525955_2'}