[PHP]Match variables? Jak sprawdzać czy input jest taki sam jak var Opcje

[masterbeat]

Witajcie, chciałbym się dowiedzieć jak zrobić skrypt który powiedzmy ma 20 var'ów

Przykład:

[HTML] pobierz, plaintext 
1980 - around 4.5 billion
1981 - around 4.5 billion
1982 - around 4.5 billion
1983 - around 4.5 billion 
1984 - around 4.5 billion
1985 - around 4.5 billion
1986 - around 4.5 billion
1987 - around 4.5 billion
1988 - around 4.5 billion
1989 - around 4.5 billion
1990 - around 5 billion
1991 - around 5 billion
1992 - around 5 billion
1993 - around 5 billion
1994 - around 5 billion
1995 - around 5 billion
1996 - around 5 billion
1997 - around 5 billion
1998 - around 5 billion
1999 - around 5 billion
2000 - around 6 billion
2001 - around 6 billion
2002 - around 6 billion
2003 - around 6 billion
2004 - around 6 billion 
2005 - around 6 billion
2006 - around 6 billion
2007 - around 6 billion
2008 - around 6 billion
2009 - around 6 billion
2010 - around 7 billion
2011 - around 7 billion
2012 - around 7 billion
2013 - around 7 billion
2014 - around 7 billion
[HTML] pobierz, plaintext 

i chciałbym aby użytkownik wpisywał w

[HTML] pobierz, plaintext 
 <input type="text" class="form-control" id="exampleInputEmail1" placeholder="Year">
[HTML] pobierz, plaintext 

np 2008 i by mu się wyświetlił tekst= " around 6 billion"