Question: An Evening with Olivia Newton-John was which number concert tour by Australian singer Olivia Newton-John, the second leg began only in February 2009, with the opening concert having Barry Gibb  as special guest on some songs?

Context paragraphs:
Olivia's Greatest Hits Vol. 2: Olivia's Greatest Hits Vol.  2 is the second hits collection from English-born, Australian pop singer Olivia Newton-John released in September 1982.  The album compiled most singles released by Newton-John since the release of her 1977 "Olivia Newton-John's Greatest Hits" album from her following albums and soundtracks.  The album included two new recordings; "Heart Attack" and "Tied Up".  Both songs were released as singles and reached number 3 and 38 on the pop charts, respectively.  "Heart Attack" was a number one single in France.

Live at the Sydney Opera House: Olivia Newton-John and the Sydney Symphony Orchestra: Live at the Sydney Opera House is a HD video (16:9) released in 2008 for a tour of four concerts at the Sydney Opera House of singer Olivia Newton-John.  The show was done in March 2006 with her band and Sydney Symphony conducted by Rick King.  Produced by Olivia's Gaia Productions.

An Evening with Olivia Newton-John: An Evening with Olivia Newton-John was fifteenth concert tour by Australian singer Olivia Newton-John.  The tour first leg began in October 2007 and was until November of that year.  The second leg began only in February 2009 and lasted until March of that year, with the opening concert having Barry Gibb as special guest on some songs.  The tour went through the North American countries the United States and Canada.

Heartstrings World Tour: The Heartstrings World Tour is the twelfth concert tour (and third world-tour) by English-born Australian pop singer Olivia Newton-John.  It began in 2002 and went through until 2005, with shows in North America, Australia and Japan during that time, she supported the three Newton-John albums "(2)", "", and "Stronger Than Before".

Olivia Newton-John 2006 World Tour: The 2006 World Tour was the twelfth concert tour by Australian singer Olivia Newton-John.  The tour had two legs, first in Japan, and second in Australia.  A tour recording in Australia was released on DVD and CD, by EMI.

Body Heart &amp; Spirit Tour: The Body Heart & Spirit Tour was the fourteenth concert tour by Australian singer Olivia Newton-John.  The tour, which went through four Asian countries, is a continuation of North American tour Grace and Gratitude Tour, also giving support to her twenty-second album, "Grace and Gratitude".  It's the first time that Newton-John visits this countries for a tour.

Barry Gibb: Barry Alan Crompton Gibb, {'1': ", '2': ", '3': ", '4': "} (born 1 September 1946) is a singer, songwriter, musician, and record producer who rose to worldwide fame as a co-founder of the group Bee Gees, one of the most commercially successful and critically acclaimed groups in the history of popular music, with his brothers, Robin and Maurice Gibb.  The three brothers also formed a songwriting partnership beginning in 1966.

A Summer Night with Olivia Newton-John: A Summer Night with Olivia Newton-John was the eighteenth concert tour by Australian singer Olivia Newton-John, in support of her sixth soundtrack "A Few Best Men".  The tour name drifts from her 1978 hit, "Summer Nights", from the musical film "Grease".  It is Newton-John largest tour since the Heartstrings World Tour, which runs from 2002 to 2005.  It was her first tour in the United Kingdom in over 30 years.

One Woman's Journey Tour: One Woman's Journey Tour was the eighth concert tour by Australian singer Olivia Newton-John.  It promotes her seventeenth studio album, "Back with a Heart".  The tour was announced after the success of the Greatest Hits Tour, and had 30 dates across the United States.

Physical Tour: The Physical Tour was the fifth concert tour by Australian singer Olivia Newton-John, in support of her 12th studio album, "Physical" (1981).  The tour consisted of 64 shows in North America only, the second largest by Newton-John, visiting arenas and stadiums.  It's the first concert tour by Newton-John since 1978 and her last in 16 years, until The Main Event Tour.

Supporting paragraphs: An Evening with Olivia Newton-John Barry Gibb
Answer: fifteenth