1979 was a year of many deaths, including British Conservative MP, Airey Neave, 18 British Army soldiers in the Warrenpoint ambush, Lord Mountbatten and others of his family, and a number of Royal Ulster Constabulary officers. The Pope visited the Republic of Ireland that year and prayed for peace.
Where the little girl fits into this is unclear, but there may well have been other civilian casualties less widely known about.
Other than that, it seems that Tommy has looked at how things developed every 10 years, as he mentions 1969, 1979, 1989 and 1999.