baɪ ðə tˈaɪm pɹədˈʌkʃən pˈiːkt dˈʊɹɹɪŋ wˈɜːld wˈɔːɹ ˈaɪ, tˈɛn mˈaɪnz ɛmplˈɔɪd tˈuː,zˈiəɹoʊzˈiəɹoʊ zˈiəɹoʊ mˈaɪnɚz ænd pɹədˈuːst wˈʌn mˈɪliən tˈʌnz ʌv kˈoʊl ˈænjuːəli.
By the time production peaked during World War I, 10 mines employed 2,000 miners and produced 1 million tonnes of coal annually.