Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Volume:Issue | Issue Date(s) | Weeks on Top | Song | Artist |
| --- | --- | --- | --- | --- |
| 20:20-21 | 29 December 1973 – 5 January 1974 | 2.0 | " The Most Beautiful Girl in the World " | Charlie Rich |
| 20:22-23 | 12 – 19 January | 2.0 | " Time in a Bottle " | Jim Croce |
| 20:24-26, 21:1 | 26 January – 16 February | 4.0 | " Seasons in the Sun " | Terry Jacks |
| 21:2 | 23 February | 1.0 | " The Way We Were " | Barbra Streisand |
| 21:3 | 2 March | 1.0 | " Love's Theme " | Love Unlimited Orchestra |
| 21:4 | 9 March | 1.0 | " Spiders and Snakes " | Jim Stafford |
| 21:5 | 16 March | 1.0 | " A Love Song " | Anne Murray |
| 21:6-7 | 23 March | 2.0 | " Rock On " | David Essex |
| 21:8 | 30 March – 6 April | 1.0 | " Sunshine on My Shoulders " | John Denver |
| 21:9-10 | 13 – 20 April | 2.0 | " Bennie and the Jets " | Elton John |
| 21:11 | 27 April - 4 May | 2.0 | " TSOP " | MFSB |
| 21:12-13 | 11 May - 18 May | 2.0 | " The Loco-Motion " | Grand Funk |
| 21:14 | 25 May | 1.0 | " The Entertainer " | Marvin Hamlisch |
| 21:15 | 1 June | 1.0 | " The Streak " | Ray Stevens |
| 21:16 | 8 June | 1.0 | " Band on the Run " | Paul McCartney and Wings |
| 21:17-19 | 15 – 29 June | 3.0 | " Sundown " | Gordon Lightfoot |
| 21:20 | 6 July | 1.0 | " Billy Don't Be a Hero " | Bo Donaldson and The Heywoods |
| 21:21-22 | 13 – 20 July | 2.0 | " Rock the Boat " | Hues Corporation |
| 21:23 | 27 July | 1.0 | " Rock Your Baby " | George McCrae |
| 21:24 | 3 August | 1.0 | " Annie's Song " | John Denver |
| 21:25-26 | 10 – 17 August | 2.0 | " Don't Let the Sun Go Down on Me " | Elton John |
| 22:1 | 24 August | 1.0 | " Feel Like Makin' Love " | Roberta Flack |
| 22:2 | 31 August | 1.0 | " (You're) Having My Baby " | Paul Anka |
| 22:3 | 7 September | 1.0 | " I Shot the Sheriff " | Eric Clapton |
| 22:4-5 | 14 – 21 September | 2.0 | " Rock Me Gently " | Andy Kim |
| 22:6 | 28 September | 1.0 | " Another Saturday Night " | Cat Stevens |
| 22:7 | 5 October | 1.0 | " I Honestly Love You " | Olivia Newton-John |
| 22:8 | 12 October | 1.0 | " Beach Baby " | The First Class |
| 22:9 | 19 October | 1.0 | " Another Saturday Night " (return) | Cat Stevens |
| 22:10 | 26 October | 1.0 | " You Haven't Done Nothin' " | Stevie Wonder |
| 22:11 | 2 November | 1.0 | " The Bitch is Back " | Elton John |
| 22:12-14 | 9 – 23 November | 3.0 | " You Ain't Seen Nothing Yet " | Bachman-Turner Overdrive |
| 22:15-17 | 30 November – 14 December | 3.0 | " My Melody of Love " | Bobby Vinton |
| 22:18-19 | 21 December - 4 January 1975 ÷ | 3.0 | " Kung Fu Fighting " | Carl Douglas |
Question:
Which song by David Essex spent 2 weeks on top of the charts?
Answer:
" Rock On "