"Twinkle, Twinkle, Little Star" is a popular English lullaby.
 The lyrics are from an early 19th-century English poem by Jane Taylor, "The Star".
 The poem, which is in couplet form, was first published in 1806 in "Rhymes for the Nursery", a collection of poems by Taylor and her sister Ann.
 It is sung to the tune of the French melody "Ah!
 vous dirai-je, maman", which was published in 1761 and later arranged by several composers including Mozart with Twelve Variations on "Ah vous dirai-je, Maman".
 The English lyrics have five stanzas, although only the first is widely known.
 It has a Roud Folk Song Index number of 7666.
 This song is usually performed in the key of C Major.
"Aiken Drum" is a popular Scottish folk song and nursery rhyme, which probably has its origins in a Jacobite song about the Battle of Sheriffmuir (1715).
 It has a Roud Folk Song Index number of 2571.
"Billy Boy" is a traditional folk song and nursery rhyme found in the United States.
 It has a Roud Folk Song Index number of 326.
 It is a variant of the traditional English folk song "My Boy Billy", collected by Ralph Vaughan Williams and published by him in 1912 as number 232 in "Novello's School Songs".
 The song is very popular with the Orange Order.
'Bye, baby Bunting' is a popular English-language nursery rhyme and lullaby.
 It has a Roud Folk Song Index number of 11018.
 "Bye, baby Bunting" is popular lullaby, used especially in schools in England and US.
'Rock-a-bye Baby' is a nursery rhyme and lullaby.
 The melody is a variant of the English satirical ballad Lillibullero .
 It has a Roud Folk Song Index number of 2768.
Effie Crockett (1857 - January 7, 1940), also known as Effie I. Canning, also known as Effie C. Carlton, was an American actress.
 She is credited with having written and composed the lullaby "Rock-a-bye Baby"; by some accounts she created the song in 1872 while babysitting.
 Because of "Rock-a-bye Baby", she is credited in over 100 films, many made decades after her death.
"The Crabfish" is a ribald humorous folk song of the English oral tradition.
 It dates back to the seventeenth century, appearing in Bishop Percy's Folio Manuscript as a song named "The Sea Crabb" based on an earlier tale.
 It has a Roud Folk Song Index number of 149.
 The moral of the story is that one should look in the chamber pot before using it.
Ten Little Indians is an American children's rhyme.
 It has a Roud Folk Song Index number of 13512.
 The word Indian usually refers to Native Americans.
 The song is traditionally performed in the tune of the Irish folk song "Michael Finnegan".
"The Twelve Days of Christmas" (Roud 68) is an English Christmas carol that enumerates in the manner of a cumulative song a series of increasingly grand gifts given on each of the twelve days of Christmas (the twelve days that comprise the Christmas season starting with Christmas Day).
 The song, published in England in 1780 without music as a chant or rhyme, is thought to be French in origin.
 "The Twelve Days of Christmas" has a Roud Folk Song Index number of 68.
 The tunes of collected versions vary.
 The standard tune now associated with it is derived from a 1909 arrangement of a traditional folk melody by English composer Frederic Austin, who first introduced the now familiar prolongation of the verse "five gold rings".
The Roud Folk Song Index is a database of nearly 200,000 references to nearly 25,000 songs that have been collected from oral tradition in the English language from all over the world.
 It is compiled by Steve Roud, a former librarian in the London Borough of Croydon.
 Roud's Index is a combination of the Broadside Index (printed sources before 1900) and a "field-recording index" compiled by Roud.
 It subsumes all the previous well-known printed sources known to Francis James Child (the Child Ballads) and includes recordings from 1900 to 1975.
 Until early 2006 the index was available only by a CD subscription; it can now be found online on a website maintained by the English Folk Dance and Song Society (EFDSS).
 A partial list is also available at List of folk songs by Roud number.

Question: What is the Roud Folk Song Index number of the lullaby Effie Crockett wrote  in 1872?
Answer: 2768