finds occurrences of a sub-string in a string

occurrences.cs

    List<Kmer> kmers = new List<Kmer>();
    string message = "gjhcebfu71uevkkvhjv,yjvykku71jrbirbgerngtgntteu71agg6g79htu718eay8hibioay+8eru71ohob8vy89egyhoih89vu71oyhbigr89yhrrvoaeoghau71e8ryg98ergh.oaeryl9g7rv7g7iytg643483gi@$#t32@#2R23r213ri4tyg2ti.88oichu71tp9hg";

    for (int i = 0; i <= message.Length - 3; i++)
    {
        string substring = message.Substring(i, 3);
        int occurences = Regex.Matches(message, Regex.Escape(substring)).Count;
        kmers.Add(new Kmer { Text = substring, Occ = occurences });
    }

    foreach (var kmer in kmers.OrderByDescending(k => k.Occ).ThenByDescending(k => k.Text).Distinct(new KMerQualty()))
    {
        Console.WriteLine($"{kmer.Text}=>{kmer.Occ} times");
    }