Angioplasty, Balloon/trends; Health Care Costs/trends; Intermittent Claudication/therapy; Ischemia/therapy; Lower Extremity/blood supply; Outcome and Process Assessment, Health Care/trends; Quality Indicators, Health Care/trends; Vascular Surgical Procedures/trends; Aged; Amputation, Surgical/economics; Amputation, Surgical/trends; Angioplasty, Balloon/adverse effects; Angioplasty, Balloon/economics; Angioplasty, Balloon/instrumentation; Angioplasty, Balloon/mortality; Chi-Square Distribution; Comorbidity; Databases as Topic; Female; Hospital Mortality; Humans; Intermittent Claudication/economics; Intermittent Claudication/mortality; Intermittent Claudication/surgery; Ischemia/economics; Ischemia/mortality; Ischemia/surgery; Length of Stay/economics; Length of Stay/trends; Limb Salvage/economics; Limb Salvage/trends; Logistic Models; Male; Odds Ratio; Outcome and Process Assessment, Health Care/economics; Patient Selection; Quality Indicators, Health Care/economics; Reoperation; Risk Assessment; Risk Factors; Stents; Time Factors; Treatment Outcome; United States/epidemiology; Vascular Surgical Procedures/adverse effects; Vascular Surgical Procedures/economics; Vascular Surgical Procedures/mortality