Drug manufacturer Amgen Inc. generated strong sales last year, but its share of the lucrative market for rheumatology and dermatology medications declined, according to the company’s 2006 annual report.The report, released Friday, showed a continued rise in sales of the drug Enbrel, manufactured by Amgen in its West Greenwich plant, one of the world’s largest biotechnology manufacturing facilities. The success of this medication has driven rapid, high-income job growth in a sector that the state’s economic-development officials are promoting.>>> Discuss This Story