How many episodes had an original air date with 5.1 million viewers
{'header': ['No. in series', 'Title', 'Directed by', 'Written by', 'U.S. viewers (million)', 'Original air date', 'Production code'], 'page_title': '', 'page_id': '', 'types': ['real', 'text', 'text', 'text', 'text', 'text', 'real'], 'id': '1-15938543-1', 'section_title': '', 'caption': '', 'rows': [['1', '" Pilot "', 'Adam Bernstein', 'Tina Fey', '8.1', 'October11,2006', '101'], ['2', '" The Aftermath "', 'Adam Bernstein', 'Tina Fey', '5.7', 'October18,2006', '102'], ['3', '" Blind Date "', 'Adam Bernstein', 'John Riggi', '6.0', 'October25,2006', '103'], ['4', '" Jack the Writer "', 'Gail Mancuso', 'Robert Carlock', '4.6', 'November1,2006', '104'], ['5', '" Jack-Tor "', 'Don Scardino', 'Robert Carlock', '5.2', 'November16,2006', '105'], ['6', '" Jack Meets Dennis "', 'Juan J. Campanella', 'Jack Burditt', '6.0', 'November30,2006', '106'], ['7', '" Tracy Does Conan "', 'Adam Bernstein', 'Tina Fey', '6.8', 'December7,2006', '107'], ['8', '" The Break-Up "', 'Scott Ellis', 'Dave Finkel & Brett Baer', '5.9', 'December14,2006', '108'], ['9', '" The Baby Show "', 'Michael Engler', 'Jack Burditt', '5.9', 'January4,2007', '109'], ['10', '" The Rural Juror "', 'Beth McCarthy', 'Matt Hubbard', '6.1', 'January11,2007', '110'], ['11', '" The Head and the Hair "', 'Gail Mancuso', 'Tina Fey & John Riggi', '5.0', 'January18,2007', '111'], ['12', '" Black Tie "', 'Don Scardino', 'Kay Cannon & Tina Fey', '5.7', 'February1,2007', '112'], ['13', '" Up All Night "', 'Michael Engler', 'Tina Fey', '5.2', 'February8,2007', '113'], ['14', '" The C Word "', 'Adam Bernstein', 'Tina Fey', '5.0', 'February15,2007', '114'], ['15', '" Hard Ball "', 'Don Scardino', 'Matt Hubbard', '4.6', 'February22,2007', '115'], ['16', '" The Source Awards "', 'Don Scardino', 'Robert Carlock & Daisy Gardner', '5.7', 'March1,2007', '116'], ['17', '" The Fighting Irish "', 'Dennie Gordon', 'Jack Burditt', '5.2', 'March8,2007', '117'], ['18', '" Fireworks "', 'Beth McCarthy', 'Dave Finkel & Brett Baer', '5.4', 'April5,2007', '118'], ['19', '" Corporate Crush "', 'Don Scardino', 'John Riggi', '5.1', 'April12,2007', '119'], ['20', '" Cleveland "', 'Paul Feig', 'Jack Burditt & Robert Carlock', '5.2', 'April19,2007', '120']], 'name': 'table_15938543_1'}